So first you want open a new terminal session and type
"su" without quotes then hit enter, type the root password then
"yum install java" without quotes, this will install openjdk not java, that's fine. then
"yum install icedtea-web" without quotes. then when you receive the link to Elive (or BB collaborate) Type your name and click the button bellow (this might be and image not loaded icon thats fine). once thats done go into download right click the downloaded JNLP file and select open with other application select open with "Icedtea webstart". then wait, it might take a while. If this dosen't work for you follow this guide on installing java runtime enviroment and try again. You do not need to set alternatives as per the guides instructions.
Here is the link to the guide on installing java runtime enviroment